The present invention relates to an internal combustion engine with pressure lubrication according to the dry sump principle, in particular for an opposed-cylinder engine.
With today's water-cooled six-cylinder opposed-cylinder engines of the 911 Carrera model series (Dr. Ing. h.c. F. Porsche A G), an oil bulkhead tank in which the oil sump for the lubricating oil supply to the engine is formed is provided in the oil carrying casing and/or in the oil pan. The oil lubricant recycled by the various consumers back to the oil pan is first returned outside of the oil bulkhead tank forming the oil suction space before entering the actual oil suction space through openings monitored by valves in the oil bulkhead tank.
In engines with dry sump lubrication, the oil flowing back into the oil pan is conveyed by a suction pump into a separate oil tank or oil supply container from which the pressure oil delivery pump sucks out the lubricant and forces it to the lubrication points through filters and oil coolers, if necessary. In most cases the oil tank is mounted on the outside of the crankcase and has corresponding connections for the oil pressure lines laid externally.
An object of the present invention is to provide a low-friction driving gear with dry sump pressure lubrication for high-speed operation in particular to increase the specific power of an internal combustion engine; in this type of operation, the components required for pressure lubrication of the internal combustion engine are largely integrated into the engine in a space-saving manner.
This object has been achieved according to this invention by providing an annular space around the cylinders as part of the oil return to the oil supply container.
According to this invention, a portion of the oil be recycled into the oil supply container and/or into the wet sump space through the annular spaces.
In particular, with cylinder crankcases of the open-deck configuration in which the water jacket is provided only in the upper part of the cylinder, there remains an annular space which is open toward the crankcase space and which can be used as part of the oil return line into the wet sump with an appropriate seal at the end. A gland made of, for example, plastic may be provided as the seal for the annular space.
When the (wet sump) oil-collecting space is arranged beneath the annular spaces provided for the oil return and/or integrated into the crankcase, the lubricating oil can be transferred directly from the annular space into the oil-collecting space(s). It is thus now possible to largely eliminate external oil lines so that this measure contributes to a compact and inexpensive implementation of an internal combustion engine with dry sump lubrication.
On the basis of the horizontal arrangement of cylinders in an opposed-cylinder engine, the annular spaces which are used for the lubricating oil return can be vented toward the top and the lubricating oil can be defoamed.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.